Preterm birth is a serious healthcare concern for mothers and their infants. The incidence of preterm birth has not been reduced in the last 40 years in spite of interventions to stop contractions of preterm labor. The cost of prematurity to society is staggering. In the United States, prematurity is the second leading cause of infant mortality and the leading cause of infant mortality for Black infants. We postulate that earlier diagnosis and treatment strategies are needed before women present with the contractions of preterm labor. Advances in the understanding of mechanisms of preterm cervical ripening have led to both animal and some human interventions to modify human cervical ripening. What is missing is an objective noninvasive method to detect changes in cervix tissue microstructure consistent with cervical ripening. The long-term goal of this research program is to develop a noninvasive ultrasound technique that will detect early cervical ripening in humans and lead to scientific interventions to modify preterm birth. Cervical shortening and dilation can be detected with clinical ultrasound systems. However, an objective noninvasive method to determine tissue property changes (increased collagen disorganization and water concentration) associated with cervical ripening does not exist. Estimates of ultrasound attenuation (the loss of energy as an ultrasonic wave propagates through tissue) have been used to evaluate the structure and function of tissue in health and disease. Attenuation has been found to be related to tissue stiffness, collagen content and water concentration of tissues. We want to translate our capabilities to detect cervical tissue changes in the animal model to those changes in human pregnancy by assessing cervical attenuation in two samples of pregnant women. In the first sample (n = 25), we will conduct six assessments of cervical attenuation over the course of human pregnancy to determine whether differences can be detected and whether women can be recruited/retained in a longitudinal study. In the second sample (n = 20), we will determine whether estimates of attenuation can detect changes in the cervix associated with medically induced cervical ripening (a known process where marked cervix tissue changes occur in a short time frame). In conditions where labor must be medically induced in pregnancy, pharmacological agents such as prostaglandins can accelerate the process of cervical ripening before inducing the contractions of labor.56 Prostaglandins have been noted to produce marked cervical ripening in five to twelve hours. The specific aims of this study are to determine: Aim 1. The feasibility of recruitment and retention of pregnant women for a longitudinal ultrasound study. Aim 2. Whether longitudinal assessments of cervical attenuation in human pregnancy can detect changes in the cervix associated with cervical ripening over the course of pregnancy. Aim 3. Whether ultrasound attenuation estimates can detect differences between pre- and post medically induced cervical ripening in term human pregnancy. PUBLIC HEALTH RELEVANCE: Treatment of preterm labor has focused on treating contractions rather than the long process of cervical "ripening" or thinning that precedes preterm labor. Advances in the understanding of mechanisms of preterm cervical ripening have led to both animal and human interventions to modify human cervical ripening. What is missing is a noninvasive method to detect such changes. The long-term goal of this research program is to develop a noninvasive ultrasound technique that will detect early cervical ripening in humans and lead to scientific interventions to modify preterm birth.